/**
 *    Copyright 2010-2019 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.mybatis.spring.batch;

import static org.springframework.util.Assert.notNull;
import static org.springframework.util.ClassUtils.getShortName;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;

import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.batch.item.database.AbstractPagingItemReader;

/**
 * {@code org.springframework.batch.item.ItemReader} for reading database
 * records using MyBatis in a paging fashion.
 * <p>
 * Provided to facilitate the migration from Spring-Batch iBATIS 2 page item readers to MyBatis 3.
 *
 * @author Eduardo Macarron
 *
 * @since 1.1.0
 */
public class MyBatisPagingItemReader<T> extends AbstractPagingItemReader<T> {

    private String queryId;

    private SqlSessionFactory sqlSessionFactory;

    private SqlSessionTemplate sqlSessionTemplate;

    private Map<String, Object> parameterValues;

    public MyBatisPagingItemReader() {
        setName(getShortName(MyBatisPagingItemReader.class));
    }

    /**
     * Public setter for {@link SqlSessionFactory} for injection purposes.
     *
     * @param sqlSessionFactory a factory object for the {@link SqlSession}.
     */
    public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    /**
     * Public setter for the statement id identifying the statement in the SqlMap
     * configuration file.
     *
     * @param queryId the id for the statement
     */
    public void setQueryId(String queryId) {
        this.queryId = queryId;
    }

    /**
     * The parameter values to be used for the query execution.
     *
     * @param parameterValues the values keyed by the parameter named used in
     * the query string.
     */
    public void setParameterValues(Map<String, Object> parameterValues) {
        this.parameterValues = parameterValues;
    }

    /**
     * Check mandatory properties.
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
     */
    @Override
    public void afterPropertiesSet() throws Exception {
        super.afterPropertiesSet();
        notNull(sqlSessionFactory, "A SqlSessionFactory is required.");
        sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory, ExecutorType.BATCH);
        notNull(queryId, "A queryId is required.");
    }

    @Override
    protected void doReadPage() {
        Map<String, Object> parameters = new HashMap<String, Object>();
        if (parameterValues != null) {
            parameters.putAll(parameterValues);
        }
        parameters.put("_page", getPage());
        parameters.put("_pagesize", getPageSize());
        parameters.put("_skiprows", getPage() * getPageSize());
        if (results == null) {
            results = new CopyOnWriteArrayList<T>();
        } else {
            results.clear();
        }
        results.addAll(sqlSessionTemplate.<T>selectList(queryId, parameters));
    }

    @Override
    protected void doJumpToPage(int itemIndex) {
        // Not Implemented
    }

}
